1. Field of the Invention
The invention pertains to a rodless pressure cylinder with a cylinder housing which is provided with a longitudinal slot extending along its entire length and which has a cylindrical interior in which a longitudinally movable drive piston is arranged. A lateral attachment extends from this piston outwardly through the longitudinal slot. Cylinder caps are provided at the ends of the cylinder housing for enclosing the cylindrical interior thereof and a coupling is provided on the outside for the feed and discharge of the pressure medium which actuates the drive piston. The longitudinal slot is sealed by an interior sealing strip in the interior of the cylinder housing, which is lifted from the longitudinal slot only in the region of the attachment and penetrates through a guide channel in the drive piston. The slot is always sealed from the outside with an additional outer sealing strip which is fastened onto the outside of the cylinder housing over the longitudinal slot at its ends with clamping elements separated from the cylinder caps.
2. The Prior Art
A rodless pressure cylinder of the foregoing type of construction is disclosed in U.S. Pat. No. 5,245,910. The outer sealing strip which covers the longitudinal slot on the outside of the cylinder housing is anchored on both sides in this known apparatus by clamping elements separated from the cylinder caps on each side, the clamping elements being fastened onto the cylinder housing with two screws and each including a threaded hole for the connection of a pressure line. The threaded hole leads to the gap between the outer and inner sealing strips which extend up to the caps where a sealing is established between the clamping element holding the outer sealing strip and the inner sealing strip on the longitudinal slot. The longitudinal slot is thus sealed so that it is possible to produce a vacuum in the gap between the two sealing strips or an overpressure against the ambient pressure surrounding the pressure cylinder. In this way a leaking of pressure out of the pressure cylinder into the surrounding space or from the surrounding space into the cylinder is avoided, for example if the pressure cylinder is used in a pure or in an aggressive atmosphere. The fastening of the ends of the inner sealing strip is not described in this patent. Since the inner sealing strip is, however, exposed to a tensile load in its longitudinal direction during the operation of the pressure cylinder and the interior as well as the gap between the two sealing strips must be sealed, it must extend up to the two cylinder caps and be anchored to the cylinder housing with an elastic seal in form-locked fashion and not merely tensionally. It must therefore be presumed that the inner sealing strip is fastened to the cylinder housing in a conventional fashion by the cylinder cap.
Pressure cylinders, pneumatic or also hydraulic cylinders, require air attachments for the feed of the pressure medium actuating the working piston of the cylinder, such attachments being enabled by means of threads of various sizes for the incorporation of screwed hose couplings or also of so-called plug connectors. The connectors lie in general perpendicularly to the axis of the pressure cylinder extending horizontally between the enclosure caps of the cylinder. During use of the pressure cylinder it is often required to have the connectors feed towards the other side or towards the bottom, perhaps also upwardly, since the placement relationship requires this during mounting of the pressure cylinder.
In rod-piston cylinders having the driving force centered along the piston shaft, the prior position of the attachment on the pressure cylinder at production is not important since the cylinder is built rotationally symmetrical and a user is in a position to locate the attachment during mounting of the pressure cylinder by turning it about its axis to wherever he pleases. However, the construction forms of known cylinders with no drive rod known make the simple rotation of the cylinder impossible, since the force output does not result centrally at the end of the cylinder, but rather laterally on the cylinder through the longitudinal slot. The spatial positioning of the pressure cylinder is therefore determined by the position of the connectors for driving the equipment to be driven.
Up until now, this problem has been solved in that for each rodless pressure cylinder, various cylinder caps have been offered with connectors lying at various positions. Another solution of the problem consists of a so-called universal cap, which has three equal threaded connectors. The unused connectors must be closed by means of plugs.
The object of improving the known rodless cylinder of the type described above such that the connectors for the feed and discharge of the pressure medium can be provided off of the cylinder caps on desired sides of the cylinder in a simple way and without changing the caps establishes the basis of this invention.